Update readme

diff --git a/README.md b/README.md
index c60fa70cfd2dcfeed2082355510764f24f95ba80..22177942d5cf5594aa265e97123a055918c6e921 100644 (file)
--- a/README.md
+++ b/README.md
@@ -108,7 +108,10 @@ network interface.
 This error message could also indicate a bug in the TFTP code; try using an external tftp
 client (busybox in this example), by specifying the `-c` flag instead of the `-f` flag:
 
-`# nmrpflash -i eth0 -c "busybox tftp -p -l EX2700-V1.0.1.8.img \$IP"`
+`# nmrpflash -i eth0 -c 'busybox tftp -p -l EX2700-V1.0.1.8.img $IP'`
+
+The environment variable `IP` is set by `nmrpflash` (other environment variables
+are: `MAC`, `PORT`, `NETMASK`).
 
 ###### "Timeout while waiting for CLOSE_REQ."